Negative electrode for all-solid-state battery, all-solid-state battery comprising same, and method for manufacturing negative electrode for all-solid-state battery

Abstract

A negative electrode for an all-solid-state battery according to the present invention comprises: a negative electrode current collector; and a negative electrode coating layer disposed on the negative electrode current collector, wherein the negative electrode coating layer comprises carbon material powder, the carbon material powder comprises a carbon material and first metal nanoparticles, the average particle diameter of the first metal nanoparticles is 1 μm or less, and the average particle diameter of the carbon material powder is 100 nm to 2 μm.

Description

Anode for an all-solid-state battery, an all-solid-state battery including the same, and a method for manufacturing the anode for an all-solid-state battery

[0001] The present invention relates to a negative electrode for an all-solid-state battery, an all-solid-state battery including the same, and a method for manufacturing the negative electrode for an all-solid-state battery.

[0002]

[0003] Recent industrial demands have led to the active development of batteries with high energy density and safety. For example, lithium-ion batteries are being used not only in information and communication devices, but also in the automotive sector. Safety is particularly important in the automotive sector, as it is directly related to life.

[0004] All-solid-state batteries are being proposed, replacing the electrolyte with a solid electrolyte. By eliminating the use of flammable organic dispersion media, all-solid-state batteries can significantly reduce the risk of fire or explosion in the event of a short circuit.

[0005]

[0006] The problem to be solved by the present invention is to provide an all-solid-state battery having excellent stability and electrochemical characteristics.

[0007]

[0008] An anode for an all-solid-state battery according to embodiments of the present invention comprises: a cathode current collector; and a cathode coating layer disposed on the cathode current collector, wherein the cathode coating layer comprises carbon material powder, the carbon material powder comprises carbon material and first metal nanoparticles, the average particle diameter of the first metal nanoparticles is 1 μm or less, and the average particle diameter of the carbon material powder may be 100 nm to 2 μm.

[0009] An all-solid-state battery according to the present invention comprises: a positive electrode layer; a negative electrode layer facing the positive electrode layer; and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer; wherein the negative electrode layer comprises: a negative electrode current collector; and a negative electrode coating layer disposed on the negative electrode current collector, wherein the negative electrode coating layer may be the negative electrode coating layer.

[0010]

[0011] According to embodiments of the present invention, the cathode can have the first metal nanoparticles uniformly distributed in the carbon material. As a result, an all-solid-state battery using the cathode can have improved lifespan characteristics and stability.

[0012]

[0013] FIG. 1 is a plan view of an all-solid-state battery according to embodiments of the present invention.

[0014] Figure 2 is a cross-sectional view taken along line A-A' of Figure 1.

[0015] FIG. 3 is a cross-sectional view taken along line A-A' of FIG. 1 to explain an all-solid-state battery according to some embodiments of the present invention.

[0016] Figure 4 is a cross-sectional view of a negative electrode of an all-solid-state battery according to embodiments of the present invention.

[0017] Figure 5 is an enlarged view of the first metal nanoparticle of Figure 4.

[0018] FIG. 6 is a cross-sectional view of an all-solid-state battery according to some embodiments of the present invention.

[0019] FIG. 7 is a cross-sectional view of an all-solid-state battery during charging according to some embodiments of the invention.

[0020] Figure 8 is a flowchart for explaining a method for manufacturing a cathode according to embodiments of the present invention.

[0021] FIG. 9 is a cross-sectional view of a negative electrode of an all-solid-state battery according to some embodiments of the present invention.

[0022] Figure 10 is an enlarged view of N in Figure 9.

[0023] Figure 11a is a graph showing the particle size analysis results of a comparative example.

[0024] Figure 11b is a graph showing the particle size analysis results of an example.

[0025] Figure 12a is an SEM photograph of a comparative example.

[0026] Figure 12b is an SEM photograph of an example.

[0027] Figure 13 is a graph showing the results of measuring the life evaluation of comparative examples and examples.

[0028] Figure 14 is a graph showing the results of measuring the storage evaluation of comparative examples and examples.

[0029]

[0030]

[0031] To fully understand the structure and effects of the present invention, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but can be implemented in various forms and subject to various modifications. However, the description of these embodiments is provided solely to ensure a complete disclosure of the present invention and to fully inform those skilled in the art of the invention of the scope of the invention.

[0032] In this specification, when a component is referred to as being on another component, it means that it can be formed directly on the other component, or a third component may be interposed between them. Furthermore, in the drawings, the thicknesses of the components are exaggerated for the sake of clarity. Parts designated by the same reference numerals throughout the specification represent the same components.

[0033] Unless otherwise specified herein, the singular may also include the plural. Furthermore, unless otherwise specified, "A or B" may mean "including A, including B, or including A and B." As used herein, "comprises" and / or "comprising" do not exclude the presence or addition of one or more other components.

[0034] As used herein, “combination thereof” may mean mixtures, laminates, composites, copolymers, alloys, blends, and reaction products of the components.

[0035] As used herein, “combination thereof” may mean mixtures, laminates, composites, copolymers, alloys, blends, and reaction products of the components.

[0036] In this specification, “metal” may include both metals and metalloids such as silicon and germanium, in either the elemental or ionic state.

[0037] In this specification, “alloy” may mean a mixture of two or more metals.

[0038] In this specification, “positive electrode active material” may mean a positive electrode material capable of undergoing lithiation and delithiation.

[0039] In this specification, “negative electrode active material” may mean a negative electrode material capable of undergoing lithiation and delithiation.

[0040] In this specification, “lithiation” and “lithiating” may refer to a process of adding lithium to a positive electrode active material or a negative electrode active material.

[0041] In this specification, “delithiation” and “delithiate” may refer to a process of removing lithium from a positive electrode active material or a negative electrode active material.

[0042] In this specification, “charging” and “charging” may refer to a process of providing electrochemical energy to a battery.

[0043] In this specification, “discharging” and “discharging” may refer to the process of removing electrochemical energy from a battery.

[0044] In this specification, “positive electrode” may mean an electrode where electrochemical reduction and lithiation occur during a discharge process.

[0045] In this specification, “negative electrode” may mean an electrode where electrochemical oxidation and delithiation occur during a discharge process.

[0046] Unless otherwise defined in this specification, the particle size may be the average particle size. In addition, the particle size may be the average particle size (D), which means the diameter of particles with a cumulative volume of 50% by volume in the particle size distribution. 50 ) means the average particle diameter (D 50 ) can be measured by methods widely known to those skilled in the art, for example, by measuring with a particle size analyzer, or by measuring with a transmission electron microscope photograph or a scanning electron microscope photograph. Alternatively, a measuring device using dynamic light-scattering is used for measurement, and data analysis is performed to count the number of particles for each particle size range, and then the average particle diameter (D) is calculated from this. 50) value can be obtained. Or, it can be measured using the laser diffraction method. When measuring by the laser diffraction method, more specifically, after the particles to be measured are dispersed in a dispersion medium, they are introduced into a commercially available laser diffraction particle size measuring device (e.g., Microtrac MT 3000) and irradiated with ultrasonic waves of about 28 kHz at an output of 60 W, and then the average particle diameter (D) based on 50% of the particle size distribution in the measuring device is measured. 50 ) can be produced.

[0047] FIG. 1 is a plan view of an all-solid-state battery according to embodiments of the present invention. FIG. 2 is a cross-sectional view taken along line A-A' of FIG. 1.

[0048] Referring to FIGS. 1 and 2, the all-solid-state battery (10) according to the present invention may include a positive electrode layer (100), a negative electrode layer (200) facing the positive electrode layer (100), and a solid electrolyte layer (300) disposed between the positive electrode layer (100) and the negative electrode layer (200). However, the present invention is not limited thereto, and the all-solid-state battery (10) may further include an additional functional layer, such as an adhesion enhancing layer, disposed between the positive electrode layer (100) and the solid electrolyte layer (300) or between the negative electrode layer (200) and the solid electrolyte layer (300).

[0049] A positive electrode layer (100) according to one embodiment of the present invention may include a positive electrode current collector (110) and a positive electrode active material layer (120) disposed on the positive electrode current collector (110). The positive electrode active material layer (120) may include a positive electrode active material, a solid electrolyte, a conductive material, and a binder.

[0050] The positive electrode current collector (110) can provide a reference surface on which the positive electrode active material layer (120) is arranged. The positive electrode current collector (110) can include a plate or foil including, 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 an alloy thereof.

[0051] Meanwhile, unlike that illustrated in FIG. 2, in one embodiment of the present invention, the positive electrode current collector (110) may be omitted. Although not illustrated, a carbon layer having a thickness of 0.1 μm to 4 μm may be additionally disposed between the positive electrode current collector (110) and the positive electrode active material layer (120) to increase the bonding strength between the positive electrode current collector (110) and the positive electrode active material layer (120).

[0052] The positive electrode active material of the positive electrode active material layer (120) may include a material that can reversibly absorb and desorb lithium ions. The positive electrode active material may include a plurality of particles. The positive electrode active material may include, for example, lithium transition metal oxides such as lithium cobalt oxide (LCO), lithium nickel oxide, lithium nickel cobalt oxide, lithium nickel cobalt aluminum oxide (NCA), lithium nickel cobalt manganese oxide (NCM), lithium manganate, lithium iron phosphate, nickel sulfide, copper sulfide, lithium sulfide, iron oxide, or vanadium oxide, but is not necessarily limited thereto. The positive electrode active materials may be each alone or may be a mixture of two or more types.

[0053] Lithium transition metal oxides include, for example, Li a A 1-b B b D2(0.90≤a≤1, 0≤b≤0.5), Lia HAVE BEEN 1-b B b O 2-c D c (0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05), LiE 2-b B b O 4-c D c (0≤b≤0.5, 0≤c≤0.05), Li a Ni 1-b-c Co b B c D α (0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α<2), Li a Ni 1-b-c Co b B c O 2-α F α (0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α<2), Li a Ni 1-b-c Mr b B c D α (0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α≤2), Li a Ni 1-b-c Mr b B c O 2-α F α (0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α<2), Li a Ni b HAVE BEEN c G d O2(0.90≤a≤1, 0≤b≤0.9, 0≤c≤0.5, 0.001≤d≤0.1), Li a Ni b Co c Mr d GeO2(0.90≤a≤1, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, 0.001≤e≤0.1), Li a NiG b O2(0.9≤a≤1, 0.001≤b≤0.1), Li a CoG b O2(0.90≤a≤1, 0.001≤b≤0.1), Li a MnGb O2(0.90≤a≤1, 0.001≤b≤0.1), Li a Mn2GbO4(0.90≤a≤1, 0.001≤b≤0.1), QO2, QS2, LiQS2, V2O5, LiV2O5, LiIO2, LiNiVO4, Li 3-f J2(PO4)3(0≤f≤2), Li 3-f A compound represented by any one of Fe2(PO4)3(0≤f≤2), LiFePO4. In these compounds, the capital letter “A” is Ni, Co, Mn, or a combination thereof, the capital letter “B” is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof, the capital letter “D” is O, F, S, P, or a combination thereof, the capital letter “E” is Co, Mn, or a combination thereof, the capital letter “F” is F, S, P, or a combination thereof, the capital letter “G” is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof, the capital letter “Q” is Ti, Mo, Mn, or a combination thereof, the capital letter “I” is Cr, V, Fe, Sc, Y, or a combination thereof, and the capital letter “J” is V, Cr, Mn, Co, Ni, Cu, or a combination thereof.

[0054] The cathode active material may include, for example, a lithium salt of a transition metal oxide having a layered rock salt type structure among the lithium transition metal oxides described above. The "layered rock salt type structure" is, for example, a cubic rock salt type structure. <111> It is a structure in which oxygen atomic layers and metal atomic layers are alternately and regularly arranged in a direction, and thereby each atomic layer forms a two-dimensional plane. The "cubic rock salt structure" refers to the sodium chloride type (NaCl type) structure, which is a type of crystal structure, and specifically refers to a structure in which the face-centered cubic lattice (fcc) formed by each cation and anion is arranged with a displacement of half of the ridge of the unit lattice. Lithium transition metal oxides having this layered rock salt structure include, for example, LiNi x Co y Al z O2(NCA) or LiNi x Co y Mn z O2(NCM) (0 <x<1,0<y<1, 0<z<1, x+y+z=1) 등의 삼원계 리튬전이금속산화물일 수 있다. 양극 활물질이 층상암염형 구조를 갖는 삼원계 리튬전이금속산화물을 포함하는 경우, 전고체 전지(10)의 에너지 밀도가 커지고 열안정성이 향상될 수 있다.

[0055] The above-described compound included in the positive electrode active material may be covered by a coating layer (not shown). The positive electrode active material may also be a mixture of the above-described compound and a compound to which a coating layer is added. Meanwhile, the coating layer added to the surface of the positive electrode active material may include, for example, an oxide, a hydroxide, an oxyhydroxide, an oxycarbonate, or a hydroxycarbonate of the coating elements below. The compound forming the coating layer is amorphous or crystalline. The coating elements included in the coating layer may include Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or mixtures thereof. The coating layer may include, for example, Li2O-ZrO2 (LZO). The method for forming the coating layer is selected within a range that does not adversely affect the physical properties of the positive electrode active material. The method for forming the coating layer includes, for example, spray coating, dipping, etc.

[0056] When the positive electrode active material includes nickel (Ni) as a ternary lithium transition metal oxide such as NCA or NCM, for example, the capacity density of the all-solid-state battery (10) can be increased, thereby reducing metal dissolution of the positive electrode active material in a charged state. As a result, the cycle characteristics of the all-solid-state battery (10) in a charged state are improved. Meanwhile, the "cycle characteristics" are characteristics indicating the degree to which the all-solid-state battery (10) is deteriorated by charge / discharge of the all-solid-state battery (10). An all-solid-state battery (10) with high cycle characteristics may have a small degree of deterioration of the all-solid-state battery (10) due to charge / discharge, and an all-solid-state battery (10) with low cycle characteristics may have a large degree of deterioration of the all-solid-state battery (10) due to charge / discharge.

[0057] The positive electrode active material may have a particle shape such as a sphere or an ellipsoid, for example. The particle size and content of the positive electrode active material are not particularly limited.

[0058] The solid electrolyte of the positive electrode active material layer (120) may have a particle shape. The solid electrolyte may be dispersed between the positive electrode active materials. The solid electrolyte may include a sulfide-based solid electrolyte having excellent lithium ion conductivity characteristics. Examples of the sulfide-based solid electrolyte include Li2S-P2S5, Li2S-P2S5-LiX (X is a halogen element), 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, Li2S-P2S5-Z m S n (m, n are positive numbers, capital letter “Z” represents Ge, Zn or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (p, q are positive numbers, capital letter “M” is one of P, Si, Ge, B, Al, Ga In), 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 include at least one selected from (0≤x≤2).

[0059] Sulfide-based solid electrolytes include, for example, Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2), and Li 7-x PS 6-x I xIt may be an argyrodite-type compound including at least one selected from (0≤x≤2). In particular, the sulfide-based solid electrolyte may be an argyrodite-type compound including at least one selected from Li3PS4Li6PS5Cl, Li6PS5Br, and Li6PS5I.

[0060] Alternatively, the sulfide-based solid electrolyte is Li 7-a M a PS 6-c X c It may be an argyrodite-type compound containing (0≤a≤2, (0≤c≤2)), where X may be F, Br, Cl, or a combination thereof. M is candium (Sc), yttrium (Y), titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta), chromium (Cr), molybdenum (Mo), tungsten (W), manganese (Mn), technetium (Tc), rhenium (Re), iron (Fe), ruthenium (Ru), osmium (Os), cobalt (Co), rhodium (Rh), iridium (Ir), nickel (Ni), palladium (Pd), platinum (Pt), copper (Cu), silver (Ag), gold (Au), zinc (Zn), cadmium (Cd), mercury (Hg), aluminum (Al), gallium (Ga), indium (In), thallium (Tl), silicon (Si), germanium (Ge), tin (Sn), lead (Pb), arsenic (As), antimony (Sb), bismuth (Bi), or a combination thereof. Can be.

[0061] The density of the argyrodite-type solid electrolyte may be 1.5 g / cc to 2.0 g / cc. Since the argyrodite-type solid electrolyte has a density of 1.5 g / cc or more, the internal resistance of the all-solid-state battery is reduced, and the defect of the solid electrolyte membrane being penetrated and short-circuited due to the formation of lithium dendrites can be prevented. The elastic modulus of the solid electrolyte may be, for example, 15 GPa to 35 GPa.

[0062] The solid electrolyte in the positive electrode active material layer (120) may have a smaller average particle diameter than the first and second solid electrolytes in the solid electrolyte layer (300) described later. For example, the average particle diameter of the solid electrolyte in the positive electrode active material layer (120) may be 90% or less, 80% or less, 70% or less, 60% or less, 50% or less, 40% or less, 30% or less, or 20% or less of the average particle diameter of the solid electrolyte in the solid electrolyte layer (300). Meanwhile, the average particle diameter may be a median diameter measured using a laser particle size distribution meter.

[0063] The positive electrode active material layer (120) may include a conductive material. The conductive material may have conductivity without causing a chemical change in the all-solid-state battery (10), thereby increasing the conductivity of the positive electrode active material and the solid electrolyte. The conductive material may include a carbon-based material. The conductive material may include, for example, one or more selected from graphite, carbon black, acetylene black, carbon nanofibers, and carbon nanotubes.

[0064] The positive electrode active material layer (120) may further include a binder. The binder may bind the positive electrode active material, the solid electrolyte, and the conductive material within the positive electrode active material layer (120) to each other. The binder may include a material for improving the bonding strength between the positive electrode active material layer (120) and the positive electrode current collector (110). The binder may include, for example, polyvinylidene fluoride, styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, vinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, and polymethyl methacrylate.

[0065] Based on 100 parts by weight of the total of the positive electrode active material, the solid electrolyte, the conductive material, and the binder, the positive electrode active material layer (120) may include 85 parts by weight or more and 92 parts by weight or less of the positive electrode active material. Based on 100 parts by weight of the total of the positive electrode active material, the solid electrolyte, the conductive material, and the binder, the positive electrode active material layer (120) may include 0.5 parts by weight or more and 1.5 parts by weight or less of the binder.

[0066] Based on 100 parts by weight of the solid electrolyte, the positive electrode active material layer (120) may include 1 part by weight or more and 50 parts by weight or less of a conductive material. If the conductive material is included in the positive electrode active material layer (120) in an amount of less than 1 part by weight based on 100 parts by weight of the solid electrolyte, the proportion of the conductive material may decrease, thereby lowering the electrical conductivity of the positive electrode active material layer (120). If the conductive material is included in the positive electrode active material layer (120) in an amount of more than 50 parts by weight based on 100 parts by weight of the solid electrolyte, the proportion of the conductive material may be excessively high, so that a covering layer covering the surface of the solid electrolyte may not be properly formed.

[0067] The positive electrode active material layer (120) may further include additives such as fillers, coating agents, dispersants, and ion conductive aids in addition to the above-described positive electrode active material, solid electrolyte, conductive agent, and binder.

[0068] The negative electrode layer (200) may include a negative electrode current collector (210) and a negative electrode coating layer (220) on the negative electrode current collector (210). The negative electrode current collector (210) may provide a reference surface on which the negative electrode coating layer (220) is disposed. The negative electrode current collector (210) may include, for example, a material that does not react with lithium, i.e., does not form an alloy or a compound with lithium. For example, the negative electrode current collector (210) may include at least one metal selected from the group consisting of copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), and nickel (Ni). The thickness of the negative electrode current collector (210) may be 1 μm to 20 μm, more specifically 5 μm to 15 μm, and more specifically 7 μm to 10 μm.

[0069] The negative electrode current collector (210) may be composed of one of the above-described metals, or may include an alloy or coating material of two or more metals. The negative electrode current collector (210) may have, for example, a plate shape or a foil shape. Meanwhile, in one embodiment, the negative electrode current collector (210) may be omitted.

[0070] The negative electrode coating layer (220) can allow lithium metal to grow between it and the negative electrode current collector (210) when the all-solid-state battery (10) is charged. The negative electrode coating layer (220) can act as a protective layer for the lithium metal and simultaneously suppress the precipitation and growth of lithium dendrites.

[0071] The cathode coating layer (220) may include a metal and carbon. For example, the cathode coating layer (220) may include at least one metal selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). The cathode coating layer (220) may include at least one carbon selected from the group consisting of carbon black, acetylene black, furnace black, ketjen black, and graphene. In one embodiment, the cathode coating layer (220) may include a mixture of carbon black and silver (Ag).

[0072] The cathode coating layer (220) may further include additives other than metal and carbon. The cathode coating layer (220) may further include, for example, at least one additive selected from the group consisting of a binder, a filler, a coating agent, a dispersant, and an ion conductive additive.

[0073] The binder included in the above cathode coating layer (220) may include at least one of styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride (PVDF), polyethylene, vinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, and polymethyl methacrylate.

[0074] The binder may be included in an amount of 1 to 30 parts by weight based on 100 parts by weight of the cathode coating layer (220). For example, the binder may be included in an amount of 5 to 15 parts by weight based on 100 parts by weight of the cathode coating layer (220).

[0075] Meanwhile, although not shown, a carbon layer may be further included to improve adhesion between the cathode coating layer (220) and the solid electrolyte layer (300).

[0076] A solid electrolyte layer (300) may be provided between the positive electrode layer (100) and the negative electrode layer (200). The solid electrolyte layer (300) may include a sulfide-based solid electrolyte having excellent lithium ion conductivity characteristics. The solid electrolyte in the solid electrolyte layer (300) may be the same as or different from any one of the materials included in the solid electrolyte in the positive electrode active material layer (120) described above.

[0077] The solid electrolyte layer (300) may include a first solid electrolyte layer (310) and a second solid electrolyte layer (320). The first solid electrolyte layer (310) may be adjacent to the positive electrode layer (100), and the second solid electrolyte layer (320) may be adjacent to the negative electrode layer (200).

[0078] Referring to FIG. 2, the first solid electrolyte layer (310) may include a first solid electrolyte. The first solid electrolyte may have a particle shape such as a sphere or an ellipsoid. The first solid electrolyte may include a sulfide-based solid electrolyte. The first solid electrolyte may be amorphous, crystalline, or a mixture thereof. In addition, the solid electrolyte may include, for example, at least sulfur (S), phosphorus (P), and lithium (Li) as constituent elements among the above-described sulfide-based solid electrolyte materials. For example, the solid electrolyte may be a material including Li2S-P2S5. When using a sulfide-based solid electrolyte material including Li2S-P2S5 to form the solid electrolyte, the mixing molar ratio of Li2S and P2S5 is, for example, in the range of Li2S:P2S5=50:50 to 90:10.

[0079] In one embodiment, the first solid electrolyte is 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 xThe first solid electrolyte may include an argyrodite-type compound including at least one selected from (0≤x≤2). The first solid electrolyte may include an argyrodite-type compound including at least one selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I.

[0080] In another embodiment, the first solid electrolyte is Li 7-a M a PS 6-c X c Argyrodite-type compounds may include, wherein X may be Cl, Br, or a combination thereof. M may be Na, K, Fe, Mg, Ca, Ag, Cu, Zr, Zn, or a combination thereof. Each of a and c may be a real number between 0 and 2.

[0081] The density of the argyrodite-type solid electrolyte may be 1.5 g / cc to 2.0 g / cc. When the argyrodite-type solid electrolyte has a density of 1.5 g / cc or more, the internal resistance of the all-solid-state battery is reduced, and the defect of the solid electrolyte membrane being penetrated and short-circuited due to the formation of lithium dendrites can be prevented. The elastic modulus of the first solid electrolyte is, for example, 15 GPa to 35 GPa.

[0082] The first solid electrolyte layer (310) may further include a binder. The binder included in the solid electrolyte layer (300) may be, for example, styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, etc., but is not limited thereto. The binder of the first solid electrolyte layer (310) may be the same as or different from the binder included in the positive electrode active material layer (120) or the binder included in the negative electrode coating layer (220).

[0083] The second solid electrolyte layer (320) may include a second solid electrolyte. The second solid electrolyte may have a particle shape such as a sphere or ellipsoid.

[0084] The second solid electrolyte may include a sulfide-based solid electrolyte. The description of the second solid electrolyte may be the same as or similar to that described above for the first solid electrolyte. In one embodiment, the second solid electrolyte may have substantially the same composition as the first solid electrolyte. In another embodiment, the second solid electrolyte may have a similar composition to the first solid electrolyte.

[0085] The second solid electrolyte can be in direct contact with the negative electrode coating layer (220). As a result, the second solid electrolyte can suppress lithium dendrites formed between the negative electrode coating layer (220) and the negative electrode current collector (210). The second solid electrolyte can effectively suppress negative electrode side reactions. As a result, the cell performance of the all-solid-state battery (10) according to the present invention can be improved.

[0086] The first solid electrolyte layer (310) may have a first thickness (TK1), and the second solid electrolyte layer (320) may have a second thickness (TK2). The first thickness (TK1) and the second thickness (TK2) may be the same or different. In one embodiment, the first thickness (TK1) may be greater than the second thickness (TK2). For example, the first thickness (TK1) may be 1.1 to 5 times the second thickness (TK2).

[0087] Referring back to FIGS. 1 and 2, the positive electrode layer (100) and the first solid electrolyte layer (310) may form a positive electrode composite layer (CSH). The negative electrode layer (200) and the second solid electrolyte layer (320) may form a negative electrode composite layer (ASH). The positive electrode composite layer (CSH) may be laminated on the negative electrode composite layer (ASH).

[0088] The area of ​​the cathode composite layer (ASH) and the area of ​​the cathode composite layer (CSH) may be different. Specifically, the area of ​​the cathode composite layer (ASH) may be larger than that of the cathode composite layer (CSH). The cathode composite layer (CSH) may be completely overlapped within the cathode composite layer (ASH).

[0089] In one embodiment of the present invention, the first solid electrolyte layer (310) may have substantially the same area as the positive electrode layer (100). The second solid electrolyte layer (320) may have substantially the same area as the negative electrode layer (200).

[0090] Specifically, the positive electrode composite layer (CSH) may have a first width (WI1) in a first direction (D1). The negative electrode composite layer (ASH) may have a second width (WI2) in the first direction (D1). The first width (WI1) may be smaller than the second width (WI2). The positive electrode composite layer (CSH) may have a third width (WI3) in the second direction (D2). The negative electrode composite layer (ASH) may have a fourth width (WI4) in the second direction (D2). The third width (WI3) may be smaller than the fourth width (WI4).

[0091] The all-solid-state battery (10) according to the present embodiment can be manufactured by forming a negative electrode composite layer (ASH) on a first carrier film, forming a positive electrode composite layer (CSH) on a second carrier film, and then laminating the negative electrode composite layer (ASH) and the positive electrode composite layer (CSH).

[0092] FIG. 3 is a cross-sectional view taken along line A-A' of FIG. 1 to explain an all-solid-state battery according to another embodiment of the present invention. In the embodiment described below, detailed descriptions of technical features overlapping with those previously described with reference to FIGS. 1 and 2 will be omitted, and differences will be described in detail.

[0093] Referring to FIG. 3, the all-solid-state battery (10) according to the present invention may further include a gasket (GSK). The gasket (GSK) may be provided to surround the cathode composite layer (CSH). The gasket (GSK) may fill the step on the side of the all-solid-state battery (10) caused by the difference in area between the anode composite layer (ASH) and the cathode composite layer (CSH). The gasket (GSK) may surround the four side surfaces of the cathode composite layer (CSH). For example, the thickness of the gasket (GSK) may be substantially the same as the thickness of the cathode composite layer (CSH).

[0094] The upper surface of the second solid electrolyte layer (320) may include a first region in contact with the first solid electrolyte layer (310) and a second region in contact with the gasket (GSK). The second region may be a peripheral region of the upper surface of the second solid electrolyte layer (320). The second region may surround the first region.

[0095]

[0096] FIG. 4 is a cross-sectional view showing a cathode according to embodiments of the present invention. FIG. 5 is an enlarged view of M of FIG. 4. For simplicity of explanation, descriptions overlapping with those of the all-solid-state battery described with reference to FIG. 1, FIG. 3, are omitted.

[0097] Referring to FIGS. 4 and 5, a negative electrode for a secondary battery according to one embodiment may include a negative electrode layer (200). The negative electrode layer (200) may include a negative electrode current collector (210) and a negative electrode coating layer (220) disposed on the negative electrode current collector (210).

[0098] The negative electrode collector (210) may have, for example, a plate-like or foil-like shape. Meanwhile, in one embodiment, the negative electrode collector (210) may be omitted.

[0099] The BET specific surface area of ​​the above cathode coating layer (220) is 10 to 100 m 2 / g. For example, the BET specific surface area of ​​the cathode coating layer (220) may be 40 to 60 m 2 / g can be 45 to 50 m 2 / g may be.

[0100] The thickness of the cathode coating layer (220) may be, for example, 1 μm to 50 μm, 5 μm to 40 μm, 5 μm to 30 μm, 5 μm to 20 μm, 10 μm to 30 μm, 10 μm to 20 μm, or 15 μm to 25 μm.

[0101] If the thickness of the negative electrode coating layer (220) is thinner than the range described above, lithium dendrites formed between the negative electrode coating layer (220) and the negative electrode current collector (210) may cause the negative electrode coating layer (220) to collapse, thereby deteriorating the cycle characteristics of the battery. On the other hand, if the thickness of the negative electrode coating layer (220) is thicker than the range described above, the energy density of the all-solid-state battery may decrease and the internal resistance of the all-solid-state battery due to the negative electrode coating layer (220) may increase, thereby deteriorating the cycle characteristics of the all-solid-state battery.

[0102] Carbon material powder (225) may be disposed on the negative electrode current collector (210). The carbon material powder (225) may be in direct contact with the negative electrode current collector (210). The carbon material powder (225) may be in direct contact with the solid electrolyte layer (300). The carbon material powder (225) may include carbon material (221) and first metal nanoparticles (222). For example, the carbon material powder (225) may mean a secondary particle of carbon material (221) and first metal nanoparticles (222). The carbon material powder (225) may be in the form of first metal nanoparticles (222) dispersed within two or more carbon materials (221). The carbon material (221) may mean a particle in which two to 100 single particles are attached to each other. The carbon material (221) may include amorphous carbon. The amorphous carbon may include a material selected from soft carbon, hard carbon, pitch carbide, mesophase pitch carbide, calcined coke, polymer carbide, and combinations thereof. The amorphous carbon may be formed by carbonizing a carbon precursor, such as coal pitch, mesophase pitch, petroleum pitch, coal oil, petroleum heavy oil, organic synthetic pitch, or a polymer resin such as a phenol resin, a furan resin, or a polyimide resin, through a heat treatment process. The heat treatment temperature during carbonization can be controlled within a range of 500°C.

[0103] The amorphous carbon included in the carbon material (221) may include at least one carbon selected from the group consisting of carbon black, acetylene black, furnace black, and ketjen black. Compared to crystalline carbon, the amorphous carbon has relatively low hardness and toughness, and can effectively suppress the volume expansion of the first metal nanoparticles (222) dispersed within the carbon material (221), thereby improving the cycle life characteristics.

[0104] Carbon material (221) has an average particle diameter (D 50 ) may be in the form of aggregates of single particles of 10 nm to 500 nm. The average particle diameter (D) of the carbon material (221) 50 ) may be 2 μm or less, for example, 100 nm to 2 μm or 0.1 μm to 0.8 μm. The average particle diameter of the carbon material powder (225) may be 0.1 μm to 1 μm. When the above range is satisfied, the first metal nanoparticles (222) can be uniformly distributed within the carbon material (221).

[0105] The BET surface area of ​​carbon material (221) is 40 to 70 m 2 / g. For example, the BET specific surface area of ​​the carbon material (221) is 55 to 60 m 2 / g. When the above range is satisfied, the carbon material (221) may have appropriate ionic conductivity, making it easy to transfer lithium ions to the surface or interior of the first metal nanoparticle (222).

[0106] A first metal nanoparticle (222) may be arranged in a carbon material powder (225). The first metal nanoparticle (222) may include silver. The average particle diameter of the first metal nanoparticle (222) may be smaller than the average particle diameter of the second metal nanoparticle (223) described later. The average particle diameter of the first metal nanoparticle (222) may be, for example, 1 μm or less, and preferably, 300 nm or less. For example, it may be 0.01 μm to 1 μm, 0.05 μm to 1 μm, 0.01 μm to 0.1 μm, 0.02 μm to 0.08 μm, or 0.03 μm to 0.06 μm. When the above range is satisfied, the first metal nanoparticle (222) may be uniformly distributed in the carbon material powder (221).

[0107] The content of the first metal nanoparticles (222) in the cathode coating layer (220) may be greater than the content of the second metal nanoparticles (223) in the cathode coating layer (220). For example, the content of the first metal nanoparticles (222) in the cathode coating layer (220) may be 1,000 to 100,000 times the content of the second metal nanoparticles (223) in the cathode coating layer (220).

[0108] The content (222) of the first metal nanoparticles in the cathode coating layer (220) may be, for example, 10 wt% to 50 wt%. When the content of the first metal nanoparticles (222) satisfies the above-described range, a cathode having excellent charge / discharge capacity while maintaining its structure can be provided.

[0109] The weight ratio of the first metal nanoparticles (222) to the carbon material (221) may be 1:1 to 1:9. For example, the weight ratio of the first metal nanoparticles (222) to the carbon material (221) may be 1:5 to 1:8. When the above range is satisfied, the formation of the cathode coating layer (220) in which the first metal nanoparticles (222) are dispersed within the carbon material (221) may be facilitated.

[0110] Second metal nanoparticles (223) may be arranged in the cathode coating layer (220). The second metal nanoparticles (223) may include silver. The second metal nanoparticles (223) may be, for example, metal aggregates in which carbon material and / or silver are aggregated. The average particle diameter of the second metal nanoparticles (223) may be larger than the average particle diameter of the first metal nanoparticles (222), and may be, for example, greater than 1.0 μm and less than or equal to 1.5 μm, 1.01 μm to 1.3 μm, 1.01 μm to 1.2 μm, or 1.1 μm to 1.5 μm. The content of the second metal nanoparticles (223) in the cathode coating layer (220) may be, for example, 0.0001 wt% to 0.05 wt%. According to some embodiments of the present invention, the cathode coating layer (220) may not include second metal nanoparticles (223).

[0111] The above cathode coating layer (220) may further include a binder and a dispersant. The binder may be, for example, one or more selected from the group consisting of styrene butadiene rubber (SBR), polyvinylidene fluoride, polytetrafluoroethylene, polyvinylidene fluoride, vinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, and polymethyl methacrylate.

[0112] The dispersant is not particularly limited, but may be one or more selected from the group consisting of, for example, a soluble polyamine, a soluble amine compound, a fatty acid, a fatty alcohol, a cellulose ion exchanger, and a sorbitan fatty acid ester, as long as it improves the dispersibility of the carbon material and does not significantly reduce the adhesiveness. For example, carboxymethyl cellulose (CMC) can be used as the dispersant.

[0113]

[0114] FIG. 6 is a cross-sectional view of an all-solid-state battery according to another embodiment of the present invention. Detailed descriptions of technical features that overlap with those described with reference to FIG. 1 and FIG. 5 above will be omitted, and differences will be described in detail.

[0115] Referring to FIG. 6, an all-solid-state battery (10) according to another embodiment may include a positive electrode layer (100), a negative electrode layer (200) facing the positive electrode layer (100), and a solid electrolyte layer (300) disposed between the positive electrode layer (100) and the negative electrode layer (200). The negative electrode layer (200) may include a negative electrode current collector (210), and a negative electrode coating layer (220) disposed on the negative electrode current collector.

[0116] The negative electrode layer (200) of the all-solid-state battery of FIG. 6 may have the same configuration as the negative electrode layer (200) described with reference to FIGS. 4 and 5.

[0117] The cathode layer (200) may include a cathode current collector (210) and a cathode coating layer (220) disposed on the cathode current collector (210). The cathode layer may include carbon material powder (225) and second metal nanoparticles (223).

[0118] Specifically, the cathode coating layer (220) may include carbon material (221), carbon material powder (225) including first metal nanoparticles (222), and second metal nanoparticles (223). The first metal nanoparticles (222) and the second metal nanoparticles (223) may be the same as the first metal nanoparticles (222) and the second metal nanoparticles (223) described with reference to FIG. 4.

[0119]

[0120] FIG. 7 is a cross-sectional view of an all-solid-state battery during charging according to another embodiment of the present invention. Detailed descriptions of technical features that overlap with those described with reference to FIG. 1 and FIG. 6 above will be omitted, and differences will be described in detail.

[0121] The all-solid-state battery (10) of FIG. 7 may have the same configuration as the positive electrode layer (100), negative electrode layer (200), and solid electrolyte layer (300) described with reference to FIG. 6.

[0122] Referring to FIG. 7, the negative electrode layer (200) of the all-solid-state battery (10) may further include a lithium metal layer (230) between the negative electrode current collector (210) and the negative electrode coating layer (220).

[0123] The cathode coating layer (220) can allow lithium metal to grow between it and the cathode current collector (210) when the all-solid-state battery (10) is charged.

[0124] The lithium metal layer (230) may further increase in thickness when the all-solid-state battery (10) is charged. The negative electrode coating layer (220) serves as a protective layer for the lithium metal layer (230), and at the same time, can suppress the growth of lithium dendrites from the lithium metal layer (230).

[0125] The lithium metal layer (230) may be a metal thin film containing lithium or a lithium alloy. The lithium alloy may include, but is not limited to, a Li-Al alloy, a Li-Sn alloy, a Li-In alloy, a Li-Ag alloy, a Li-Au alloy, a Li-Zn alloy, a Li-Ge alloy, a Li-Si alloy, etc., and any lithium alloy may be used. The lithium metal layer (230) may include one of these alloys or lithium. Alternatively, the lithium metal layer (230) may include various types of alloys.

[0126]

[0127] FIG. 8 is a flowchart showing the sequence of a cathode manufacturing method according to embodiments of the present invention. For simplicity of explanation, descriptions overlapping with those of the cathode described with reference to FIG. 1 and FIG. 5 are omitted.

[0128] According to embodiments of the present invention, a method for manufacturing a negative electrode may include: preparing a dispersion containing metal nanoparticles by mixing a silver nitrate (AgNO3) aqueous solution, a phenol-based reducing agent, and a reduction catalyst (S100); adding a nonionic polymer and a carbon material to the dispersion to prepare a first mixture (S200); adding an acid to the first mixture to prepare a second mixture with an adjusted pH (S300); filtering, drying, and heat-treating the second mixture to obtain metal nanoparticles dispersed in the carbon material (S400); mixing the metal nanoparticles, a solvent, and a binder to prepare a slurry (S500); and applying the slurry onto a negative electrode current collector to form a negative electrode coating layer (S600).

[0129] First, preparing a dispersion (S100) may include a process of mixing a silver nitrate (AgNO3) aqueous solution, a phenol-based reducing agent, and a reduction catalyst.

[0130] The phenolic reducing agent may include at least one selected from the group consisting of phloroglucinol, gallic acid, catechol, and resorcinol. The phenolic reducing agent may include a compound having an aromatic ring.

[0131] The above reduction catalyst may use an amine catalyst. For example, the amine catalyst may include at least one selected from the group consisting of 2-aminoethanol, 2-(methylamino)ethanol, 2-(ethylamino)ethanol, 3-aminopropanol, 3-(methylamino)propanol, 4-aminobutanol, 4-(methylamino)butanol, bis(2-hydroxyethyl)amine, tris(2-hydroxyethyl)amine, ethylenediamine, diethylenetriamine, triethylamine, ethanolamine, and triethanolamine.

[0132] The above mixing may include a process of adding a phenol-based reducing agent and a reduction catalyst to a silver nitrate (AgNO3) aqueous solution and then stirring.

[0133] In one embodiment, the mixing may be performed by stirring at 20°C to 40°C for 20 minutes to 3 hours. The mixing may be performed using a mixing method commonly known in the art, for example, using a stirrer, a high-shear mixer, etc.

[0134] The dispersion prepared through the above mixing process may include first metal nanoparticles and second metal nanoparticles. The average particle diameter (D) of the first metal nanoparticles included in the dispersion 50 ) may be less than 1 μm, for example, 0.1 μm to 1 μm, 0.5 μm to 1 μm, 0.2 μm to 0.8 μm, or 0.3 μm to 0.6 μm.

[0135] The average particle diameter of the second metal nanoparticles may be greater than 1 μm, for example, 1.01 μm to 1.5 μm, 1.01 μm to 1.3 μm, 1.01 μm to 1.2 μm, or 1.1 μm to 1.5 μm.

[0136] The content of the first metal nanoparticles in the dispersion may be greater than the content of the second metal nanoparticles. The content of the first metal nanoparticles in the dispersion may be 1,000 to 100,000 times the content of the second metal nanoparticles. Furthermore, according to some embodiments of the present invention, the dispersion may not include the second metal nanoparticles.

[0137] According to embodiments of the present invention, the metal nanoparticles can be manufactured in a colloidal state. This facilitates particle size control, and in particular, particle size uniformity can be improved.

[0138]

[0139] In the above step S100, 0.1 to 2 parts by weight of the phenol-based reducing agent may be added to 100 parts by weight of the silver nitrate (AgNO3) aqueous solution, and then stirring may be performed. In the above step S100, 0.1 to 2 parts by weight of the reduction catalyst may be added to 100 parts by weight of the silver nitrate (AgNO3) aqueous solution, and then stirring may be performed.

[0140] The process of preparing the first mixture (S200) may include a process of mixing a nonionic polymer and a carbon material into the dispersion. The mixing may be performed using a mixing method commonly known in the art, such as a stirrer or high-shear mixer.

[0141] Carbon materials may be in the form of single particles. The single particles may be in the form of individual particles. Alternatively, the single particles may be in the form of two to one hundred single particles attached to each other. Carbon materials may have an average particle diameter (D 50 ) may be in the form of aggregates of single particles of 40 nm to 50 nm. That is, the average particle diameter (D) of the carbon material 50 ) can be 300 nm to 500 nm.

[0142] The above carbon material may include at least one selected from the group consisting of carbon black, acetylene black, furnace black, ketjen black, hard carbon, graphite, and graphene.

[0143] The above reduction catalyst may use an amine catalyst. For example, the amine catalyst may include at least one selected from the group consisting of 2-aminoethanol, 2-(methylamino)ethanol, 2-(ethylamino)ethanol, 3-aminopropanol, 3-(methylamino)propanol, 4-aminobutanol, 4-(methylamino)butanol, bis(2-hydroxyethyl)amine, tris(2-hydroxyethyl)amine, ethylenediamine, and diethylenetriamine.

[0144] In the above step S200, the carbon material may be added in an amount of 5 to 20 parts by weight relative to 100 parts by weight of the dispersion, and then stirring may be performed. In the above step S200, in order to improve the dispersibility of the carbon material, a nonionic polymer may be dissolved in the first mixture, and then the carbon material may be added.

[0145] The above nonionic polymer may include polyvinylpyrrolidone (PVP).

[0146] The process of preparing the second mixture (S300) may include a process of adjusting the pH of the first mixture. In step S300, by adjusting the pH, metal nanoparticles can be uniformly adsorbed within the carbon material. The pH can be adjusted to a pH of 1 to 3 by adding acid to the first mixture. For example, the pH can be adjusted to a pH of 1.5 to 2.

[0147] The acid may include at least one selected from the group consisting of nitric acid, hydrochloric acid, acetic acid, formic acid, succinic acid, citric acid, malic acid, maleic acid, oxalic acid and mixtures thereof.

[0148] Obtaining metal nanoparticles dispersed within the carbon material (S400) may include a process of separating the second mixture into a liquid and a solid. In step S400, the second mixture may be filtered to separate the solid from the solvent. The solid separated from the solvent may be dried through heat treatment. The drying may be performed at a temperature of 40°C to 60°C. In addition, the drying time may be 2 to 24 hours, but is not limited thereto.

[0149] The dried product can be subjected to a calcination process to remove impurities. The calcination can be performed at temperatures ranging from 300°C to 1000°C. The calcination time can range from 1 hour to 5 hours. In one embodiment, the calcination equipment can be a variety of furnaces. For example, it can be a box-type furnace, or, considering productivity, a rotary kiln capable of continuous processing. Through this process, carbon powder can be obtained.

[0150] The process of preparing a slurry (S500) may include a process of mixing the obtained metal nanoparticles, a solvent, a dispersant, and a binder. The binder and dispersant refer to the cathode portion described above.

[0151] Forming a cathode coating layer (S600) may include a process of applying the slurry onto a cathode current collector. The cathode current collector refers to the cathode portion described above.

[0152] For example, the negative electrode coating layer can be manufactured by bar coating a slurry containing a carbon material, a binder, and a solvent in which first and second metal nanoparticles are dispersed, on a negative electrode current collector (210).

[0153] The slurry formed on the negative electrode current collector can be dried through a heat treatment process. In one embodiment, the negative electrode having a negative electrode coating layer formed thereon can be manufactured by drying the slurry-coated negative electrode current collector in a vacuum oven.

[0154] The thickness of the cathode coating layer may be 1 μm to 50 μm, 5 μm to 40 μm, 5 μm to 30 μm, 5 μm to 20 μm, 10 μm to 30 μm, 10 μm to 20 μm or 15 μm to 25 μm.

[0155]

[0156] Fig. 9 is a cross-sectional view showing a cathode according to some embodiments of the present invention. Fig. 10 is an enlarged view of N of Fig. 9. For simplicity of explanation, descriptions overlapping with those of the cathode described with reference to Figs. 1 to 5 are omitted.

[0157] Referring to FIGS. 9 and 10, the first metal nanoparticle (222) may include a core portion (11) including silver; and a shell portion (12) surrounding the core portion (11) and including carbon.

[0158] The first metal nanoparticle (222) has a structure in which a core portion (11) and a shell portion (12) are arranged on the surface of the core portion (11), thereby forming an alloy with lithium and allowing lithium to be uniformly deposited between the negative electrode coating layer and the negative electrode current collector.

[0159] The thickness (12W) of the above shell portion (12) may be, for example, 2 nm to 5 nm. When the thickness (12W) is within the above range, the battery performance improvement effect due to the structural stabilization of the first metal nanoparticle (222) may be significant.

[0160] The shell portion (12) may include carbon atoms, and may include, for example, an aromatic compound. The shell portion (12) may form, for example, a first metal nanoparticle (222) through a ligand bond with the core portion (11). The shell portion (12) may form, for example, a first metal nanoparticle (222) by adsorbing carbon onto the surface of the core portion (11). The shell portion (12) may be derived from, for example, a phenol-based reducing agent, which will be described later.

[0161] The content of the carbon atoms may be comprised between 0.1 at% and 3 at% of the total weight of the first metal nanoparticle (222). When the content of the carbon atoms satisfies the above range, the first metal nanoparticle (222) having excellent capacity may be provided. According to some embodiments of the present invention, unlike that illustrated, the first metal nanoparticle (222) may have a multilayer structure.

[0162] The other configuration may be substantially the same as the negative electrode of the all-solid-state battery described with reference to FIGS. 4 and 5.

[0163]

[0164] Referring again to FIG. 8, a method for manufacturing a cathode according to some embodiments of the present invention will be described. For simplicity, any description overlapping with the cathode described with reference to FIGS. 1 to 5 will be omitted.

[0165] According to embodiments of the present invention, a method for manufacturing a negative electrode may include: preparing a dispersion containing metal nanoparticles by mixing a silver nitrate (AgNO3) aqueous solution, a phenol-based reducing agent, and a reduction catalyst (S100); adding a nonionic polymer and a carbon material to the dispersion to prepare a first mixture (S200); adding an acid to the first mixture to prepare a second mixture with an adjusted pH (S300); filtering, drying, and heat-treating the second mixture to obtain metal nanoparticles dispersed in the carbon material (S400); mixing the metal nanoparticles, a solvent, and a binder to prepare a slurry (S500); and applying the slurry onto a negative electrode current collector to form a negative electrode coating layer (S600).

[0166] First, preparing a dispersion (S100) may include a process of mixing a silver nitrate (AgNO3) aqueous solution, a phenol-based reducing agent, and a reduction catalyst.

[0167] The phenolic reducing agent may include at least one selected from the group consisting of phloroglucinol, gallic acid, catechol, and resorcinol. The phenolic reducing agent may include a compound having an aromatic ring.

[0168] The above reduction catalyst may use an amine catalyst. For example, the amine catalyst may include at least one selected from the group consisting of 2-aminoethanol, 2-(methylamino)ethanol, 2-(ethylamino)ethanol, 3-aminopropanol, 3-(methylamino)propanol, 4-aminobutanol, 4-(methylamino)butanol, bis(2-hydroxyethyl)amine, tris(2-hydroxyethyl)amine, ethylenediamine, diethylenetriamine, triethylamine, ethanolamine, and triethanolamine.

[0169] The above mixing may include a process of adding a phenol-based reducing agent and a reduction catalyst to a silver nitrate (AgNO3) aqueous solution and then stirring.

[0170] In one embodiment, the mixing may be performed by stirring at 20°C to 40°C for 20 minutes to 3 hours. The mixing may be performed using a mixing method commonly known in the art, for example, using a stirrer, a high-shear mixer, etc.

[0171] The dispersion prepared through the above mixing process may include first metal nanoparticles and second metal nanoparticles. The average particle diameter (D) of the first metal nanoparticles included in the dispersion 50 ) may be less than 1 μm, and for example, may be 0.01 μm to 1 μm, 0.05 μm to 1 μm, 0.01 μm to 0.1 μm, 0.02 μm to 0.08 μm, 0.03 μm to 0.06 μm. The first metal nanoparticle may include a core portion and a shell portion as described with reference to FIGS. 9 and 10. The core portion may include silver, surround the core portion, and include carbon. The core portion may be derived from the silver nitrate (AgNO3) aqueous solution.

[0172] The shell portion may include, for example, an aromatic compound. The shell portion may form a first metal nanoparticle through a ligand bond with, for example, a core portion and a ligand containing carbon. The shell portion may be derived, for example, from carbon adsorbed onto the surface of the core portion. The shell portion may be derived, for example, from the phenol-based reducing agent. For example, the shell portion may be formed by adsorbing the phenol-based reducing agent onto the surface of the core portion. For example, the shell portion may be formed by a ligand bond between the surface of the core portion and the phenol-based reducing agent.

[0173] The average particle diameter of the second metal nanoparticles may be greater than 1 μm, for example, 1.01 μm to 1.5 μm, 1.01 μm to 1.3 μm, 1.01 μm to 1.2 μm, or 1.1 μm to 1.5 μm. The second metal nanoparticles may be derived from the silver nitrate (AgNO3) aqueous solution.

[0174] The content of the first metal nanoparticles in the dispersion may be greater than the content of the second metal nanoparticles. The content of the first metal nanoparticles in the dispersion may be 1,000 to 100,000 times the content of the second metal nanoparticles. Furthermore, according to some embodiments of the present invention, the dispersion may not include the second metal nanoparticles.

[0175] According to embodiments of the present invention, the metal nanoparticles can be manufactured in a colloidal state. This facilitates particle size control, and in particular, particle size uniformity can be improved.

[0176]

[0177] In the above step S100, 0.1 to 2 parts by weight of the phenol-based reducing agent may be added to 100 parts by weight of the silver nitrate (AgNO3) aqueous solution, and then stirring may be performed. In the above step S100, 0.1 to 2 parts by weight of the reduction catalyst may be added to 100 parts by weight of the silver nitrate (AgNO3) aqueous solution, and then stirring may be performed.

[0178] The process of preparing the first mixture (S200) may include a process of mixing a nonionic polymer and a carbon material into the dispersion. The mixing may be performed using a mixing method commonly known in the art, such as a stirrer or high-shear mixer.

[0179] Carbon materials may be in the form of single particles. The single particles may be in the form of individual particles. Alternatively, the single particles may be in the form of two to one hundred single particles attached to each other. Carbon materials may have an average particle diameter (D 50 ) may be in the form of aggregates of single particles of 40 nm to 50 nm. That is, the average particle diameter (D) of the carbon material 50 ) can be 300 nm to 500 nm.

[0180] The above carbon material may include at least one selected from the group consisting of carbon black, acetylene black, furnace black, ketjen black, hard carbon, graphite, and graphene.

[0181] The above reduction catalyst may use an amine catalyst. For example, the amine catalyst may include at least one selected from the group consisting of 2-aminoethanol, 2-(methylamino)ethanol, 2-(ethylamino)ethanol, 3-aminopropanol, 3-(methylamino)propanol, 4-aminobutanol, 4-(methylamino)butanol, bis(2-hydroxyethyl)amine, tris(2-hydroxyethyl)amine, ethylenediamine, and diethylenetriamine.

[0182] In the above step S200, the carbon material may be added in an amount of 5 to 20 parts by weight relative to 100 parts by weight of the dispersion, and then stirring may be performed. In the above step S200, in order to improve the dispersibility of the carbon material, a nonionic polymer may be dissolved in the first mixture, and then the carbon material may be added.

[0183] The above nonionic polymer may include at least one selected from the group consisting of polyvinylpyrrolidone (PVP), ~, ~.

[0184] The process of preparing the second mixture (S300) may include a process of adjusting the pH of the first mixture. In step S300, by adjusting the pH, metal nanoparticles can be uniformly adsorbed within the carbon material. The pH can be adjusted to a pH of 1 to 3 by adding acid to the first mixture. For example, the pH can be adjusted to a pH of 1.5 to 2.

[0185] The acid may include at least one selected from the group consisting of nitric acid, hydrochloric acid, acetic acid, formic acid, succinic acid, citric acid, malic acid, maleic acid, oxalic acid and mixtures thereof.

[0186] Obtaining metal nanoparticles dispersed within the carbon material (S400) may include a process of separating the second mixture into a liquid and a solid. In step S400, the second mixture may be filtered to separate the solid from the solvent. The solid separated from the solvent may be dried through heat treatment. The drying may be performed at a temperature of 40°C to 60°C. In addition, the drying time may be 2 to 24 hours, but is not limited thereto.

[0187] The dried product can be subjected to a calcination process to remove impurities. The calcination can be performed at temperatures ranging from 300°C to 1000°C. The calcination time can range from 1 hour to 5 hours. In one embodiment, the calcination equipment can be a variety of furnaces. For example, it can be a box-type furnace, or, considering productivity, a rotary kiln capable of continuous processing. Through this process, carbon powder can be obtained.

[0188] The process of preparing a slurry (S500) may include a process of mixing the obtained metal nanoparticles, a solvent, a dispersant, and a binder. The binder and dispersant refer to the cathode portion described above.

[0189] Forming a cathode coating layer (S600) may include a process of applying the slurry onto a cathode current collector. The cathode current collector refers to the cathode portion described above.

[0190] For example, the negative electrode coating layer can be manufactured by bar coating a slurry containing a carbon material, a binder, and a solvent in which first and second metal nanoparticles are dispersed, on a negative electrode current collector (210).

[0191] The slurry formed on the negative electrode current collector can be dried through a heat treatment process. In one embodiment, the negative electrode having a negative electrode coating layer formed thereon can be manufactured by drying the slurry-coated negative electrode current collector in a vacuum oven.

[0192] The thickness of the cathode coating layer may be 1 μm to 50 μm, 5 μm to 40 μm, 5 μm to 30 μm, 5 μm to 20 μm, 10 μm to 30 μm, 10 μm to 20 μm or 15 μm to 25 μm.

[0193]

[0194] Hereinafter, examples and comparative examples of the present invention will be described. However, the examples described below are merely examples of the present invention, and the present invention is not limited to the examples described below.

[0195]

[0196] Example

[0197] 1 g of silver nitrate (AgNO3) was dissolved in 100 ml of an aqueous solution, and 0.6 g of phloroglucinol and 0.4 g of an amine catalyst were added thereto, followed by stirring to prepare a colloidal dispersion containing silver nanoparticles at room temperature. The average particle size of the silver nanoparticles was 50 nm. A nonionic polymer (polyvinylpyrrolidone) was dissolved in the dispersion, and 10.0 g of carbon material was added to 100 g of the dispersion to prepare a first mixture. Carbon black was used as the carbon material, and the average particle size of the carbon black was 30 nm.

[0198] A second mixture with adjusted pH was prepared by adding nitric acid until the pH of the first mixture became about pH 1.5 to pH 2.

[0199] The second mixture was filtered to separate the liquid and solid, and the separated solid was dried at 60°C for 10 hours. Thereafter, the dried resultant was calcined at 700°C for 5 hours to remove impurities.

[0200] The resultant product, from which impurities were removed, was pulverized and classified to obtain carbon powder with metal nanoparticles dispersed therein.

[0201] The carbon material powder in which the metal nanoparticles were dispersed, styrene butadiene rubber (SBR) binder, and carboxymethyl cellulose (CMC) dispersant were mixed in a mass ratio of 9:0.5:0.5, and then dispersed in water and mixed to prepare a cathode coating layer slurry.

[0202] The manufactured cathode coating layer slurry was applied onto a SUS foil having a thickness of 10 μm, and a cathode coating layer was coated on the current collector, and then dried to coat the cathode coating layer on the current collector with a thickness of 20 μm. The coating was performed using a doctor blade method.

[0203]

[0204] Comparative example

[0205] A 10 μm thick SUS foil was prepared as a negative electrode current collector. 4 g of carbon powder, a mixture of carbon material and silver (Ag) particles in a weight ratio of 3:1, was placed in a container, and 4 g of an NMP solution containing 7 wt% PVDF binder (Kureha #9300) was added to prepare a mixed solution. Carbon black was used as the carbon material, and the average particle size of the carbon black was 30 nm, and the average particle size of the silver particles was 60 nm. A slurry was prepared by stirring the mixed solution while adding NMP little by little. The prepared slurry was applied to a SUS sheet using a bar coater and dried in air at 80 °C for 10 minutes to form a negative electrode coating layer on the negative electrode current collector. At this time, the negative electrode coating layer was coated with a thickness of 20 μm.

[0206]

[0207] Evaluation Example 1: Particle Size Analysis

[0208] Figure 11a shows the results of particle size analysis of carbon material powder manufactured according to a comparative example using a laser diffraction particle size analyzer. Figure 11b shows the results of particle size analysis of carbon material powder manufactured according to an example using a laser diffraction particle size analyzer.

[0209] Referring to Fig. 11a, it can be confirmed that the carbon material powder according to the comparative example has a first peak (P1) at an average particle size of 0.1 μm to 0.8 μm, a second peak (P2) at 0.8 μm to 1 μm, and a third peak (P3) at 1 μm or more. It can be confirmed that the intensity of the first peak (P1) is five times that of the second peak (P2), and the intensity of the first peak (P1) is ten times that of the third peak (P3).

[0210] Referring to Fig. 11b, it can be confirmed that the carbon material powder according to the embodiment has a fourth peak (P4) at an average particle diameter of 0.1 μm to 1 μm and a fifth peak (P5) at an average particle diameter of 1.2 μm. It can be confirmed that the intensity of the fourth peak (P4) is 100,000 times that of the fifth peak (P5).

[0211] That is, referring to FIGS. 11a and 11b, it can be confirmed that the carbon material powder according to the example has metal nanoparticles of a more uniform size than the carbon material powder according to the comparative example.

[0212]

[0213] Evaluation Example 2: Structure of metal nanoparticles (SEM)

[0214] Fig. 12a is a SEM photograph of the carbon material powder according to the comparative example. Referring to Fig. 12a, the Ag composite particles according to the comparative example were confirmed to have a shape in which multiple particles were clumped together. It can be confirmed that the Ag composite particles exist in a particle size of 1 ㎛ to 3 ㎛. In addition, it can be confirmed that the Ag-C composite particles according to the comparative example have metal (Ag) particles unevenly dispersed within the carbon material.

[0215] Fig. 12b is a SEM photograph of a carbon material powder according to an embodiment. Referring to Fig. 12b, it can be confirmed that the metal nanoparticles according to the embodiment have silver particles of 200 nm or less uniformly present in the carbon material powder of 1 μm or less. In addition, it can be confirmed that the metal nanoparticles according to the embodiment have metal (Ag) particles uniformly dispersed within the carbon material.

[0216]

[0217] Evaluation Example 3: Evaluation of All-Solid-State Battery Life Characteristics

[0218] (Polar electrode manufacturing)

[0219] LiNi0.8Co0 as a cathode active material. 15 Mn0. 05 O2 (NCM), carbon nanofibers (CNF) as a conductive material, and PVdF as a binder were mixed in a weight ratio of 98.5:0.05:1.37:0.08 in an N-methylpyrrolidone solvent to prepare a composition for forming a cathode, and the composition was loaded onto an aluminum current collector at a loading amount of 18 mg / cm. 2 The anode was manufactured by applying it as much as possible.

[0220] (Manufacturing of solid electrolyte layer)

[0221] 90 mg of a sulfide-based solid electrolyte containing Li3PS4 was placed in a mold with a diameter of 10 mm, and cold-pressed at 200 MPa to produce a solid electrolyte layer. The thickness of the solid electrolyte layer thus produced was 600 μm.

[0222] (Full cell manufacturing)

[0223] The cathodes manufactured according to the Examples and Comparative Examples, the anodes manufactured above, and the solid electrolyte layers were combined using conventional methods to fabricate full cells. The fabricated full cells were subjected to 50 charge-discharge cycles at 0.33 C at 25°C, and the lifespan efficiency after 50 charge-discharge cycles was measured. The results are shown in Table 1 below.

[0224] In Table 1, the life efficiency is expressed by the following mathematical formula 1.

[0225] <Mathematical Formula 1>

[0226] Life efficiency [%] = [100 discharge capacity / initial discharge capacity] × 100

[0227] Life Efficiency (%) Example 97.5 Comparative Example 81.5

[0228] Referring to Table 1 and Figure 13, it was found that the all-solid-state battery according to the example had significantly improved life characteristics compared to the comparative example. The present invention can improve the structural stability of the negative electrode layer by uniformly distributing metal nanoparticles of a uniform size within the carbon material.

[0229] Evaluation Example 4: DCIR Increase Rate Measurement

[0230] (Full cell manufacturing)

[0231] A full cell was manufactured by combining the negative electrode manufactured according to Examples and Comparative Examples and the positive electrode and solid electrolyte layer manufactured as in Evaluation Example 3 using a conventional method. The manufactured secondary batteries were CC / CV charged at 0.5 C, 4.2 V (cut-off condition) and CC discharged at 2.0 C, 2.5 V (cut-off condition), and then recharged and discharged at 2.0 C for 10 seconds at SOC 50% to measure the resistance value. The resistance value according to the cycle was calculated as the rate of increase compared to the resistance value of the first cycle, and the results are shown in Figure 14.

[0232] In the case of the comparative example, it can be confirmed that there is a 300% increase, while in the case of the embodiment, there is a 156% increase. That is, referring to Fig. 14, it can be confirmed that the embodiment shows superior life performance than the comparative example.

[0233]

[0234] Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications can be made within the scope of the patent claims, the detailed description of the invention, and the attached drawings, and it is obvious that this also falls within the scope of the present invention.

Claims

negative current collector; and Including a cathode coating layer disposed on the above cathode current collector, The above cathode coating layer includes carbon material powder, The above carbon material powder includes carbon material and first metal nanoparticles, The average particle diameter of the above first metal nanoparticles is 1 μm or less, The above carbon material powder is an all-solid-state battery negative electrode having an average particle diameter of 100 nm to 2 μm. In claim 1, The above cathode coating layer further includes second metal nanoparticles, The average particle diameter of the second metal nanoparticles is larger than the average particle diameter of the first metal nanoparticles, An all-solid-state battery negative electrode, wherein the content of the first metal nanoparticles in the negative electrode coating layer is greater than the content of the second metal nanoparticles in the negative electrode coating layer. In claim 2, An all-solid-state battery negative electrode, wherein the average particle diameter of the second metal nanoparticles is greater than 1 μm and less than or equal to 1.5 μm. In claims 1 and 2, An all-solid-state battery negative electrode, wherein the first metal nanoparticle and the second metal nanoparticle include at least one selected from the group consisting of Ag, Au, Sn, Zn, Al, Mg, Ge, Cu, In, Ni, Bi, Pt, and Pd. In claim 2, An all-solid-state battery negative electrode, wherein the content of the first metal nanoparticles in the negative electrode coating layer is 1,000 to 100,000 times the content of the second metal nanoparticles in the negative electrode coating layer. In claim 2, An all-solid-state battery negative electrode, wherein the content of the first metal nanoparticles in the negative electrode coating layer is 10 wt% to 50 wt%. In claim 6, An all-solid-state battery negative electrode, wherein the content of the second metal nanoparticles in the negative electrode coating layer is 0.0001 wt% to 1 wt%. In claim 1, An anode for an all-solid-state battery, wherein the carbon material comprises at least one selected from the group consisting of carbon black, acetylene black, furnace black, ketjen black, and graphene. In claim 1, An all-solid-state battery negative electrode, wherein the weight ratio of the first metal nanoparticles and the carbon material in the negative electrode coating layer is 1:1 to 1:

9. In claim 1, The above first metal nanoparticles: A core portion containing metal; It includes a shell portion that surrounds the core portion and contains carbon, An all-solid-state battery negative electrode having a shell thickness of 1 nm to 10 nm. In claim 1, An all-solid-state battery negative electrode, wherein the carbon content in the first metal nanoparticles is 0.1 at% to 3 at%. In claim 1, An all-solid-state battery negative electrode, wherein the negative electrode coating layer further comprises a binder and a dispersant. In claim 1, An all-solid-state battery negative electrode, wherein the average particle diameter of the first metal nanoparticles is 0.01 μm to 0.1 μm. In claim 1, The above carbon material has an average particle diameter (D 50 ) A cathode for a battery having a thickness of 10 nm to 500 nm. In claim 1, The above cathode coating layer further includes a binder, An all-solid-state battery negative electrode, wherein the binder comprises at least one of styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride (PVDF), polyethylene, vinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, and polymethyl methacrylate. In claim 2, The analysis results of the cathode coating layer including the carbon material, the first metal nanoparticles and the second metal nanoparticles measured by a particle size analyzer are as follows: Contains a first peak with a particle size of 0.1 μm to 1 μm or less, A second peak is included when the particle size is greater than 1 μm and less than or equal to 2 μm, An all-solid-state battery negative electrode wherein the first peak is at least 5000 times higher than the second peak. In claim 1, The above carbon material powder is an all-solid-state battery negative electrode in which first metal nanoparticles are dispersed in two or more carbon materials. In claim 1, The above carbon material powder is an all-solid-state battery negative electrode in which two or more carbon materials and first metal nanoparticles are dispersed and formed into secondary particles. bipolar layer; a cathode layer opposite to the anode layer; and Including a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer; The above cathode layer: negative current collector; and Including a cathode coating layer disposed on the above cathode current collector, An all-solid-state battery wherein the cathode coating layer is a cathode coating layer according to claim 1.

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